Introduction: In each section of the human gastrointestinal (GI) tract we may find bacteria that are adapted to local conditions and fulfill an important role in the proper functioning of the body. The gut microorganisms are crucial in human physiology in areas as diverse as the brain and the immune system functions. Therefore, there is a close relationship between the intestinal microbiota, its metabolic activity, and health of the host. Areas covered: In this review, we explore the host-microbiome interactions and characterize the role they may play in drug metabolism and toxicity. The study is based on pertinent papers that were retrieved by a selective search using relevant keywords in PubMed and ScienceDirect databases. Expert opinion: Increasing unhealthy eating habits, stress, antibiotic therapy, unfavorable environmental factors, and genetic predisposition contribute to imbalances in the composition and function of the GI tract microbes and the initiation and progression of disease processes. Restoration of the balanced gut microbiota composition is possible by oral administration of probiotics.
Keywords: Gut microbiota; drug efficacy; drug metabolism; drug toxicity; pharmacology.